Downside to 1.7 rockers and larger throttle bodies?

[ACR Joe]

Installed Belanger headers and exhaust (catless) and removed the H2O baffle in the airbox. It's an ACR so smoothies and K&N's are already there. Thats it, nothing more ..... yet!

I need more power and have been leaning toward 1.7 roller rockers and throttle bodies (65mm I believe) given the relatively modest cost and perceived power gain.

I believe peak power improves by ~ 25 rwhp. What about the low end throttle response? Will it soften a bit? Does the combination of the two negate the softening effect?

Any recommendations for sources? What about the new Arrow roller rockers that do not require the heads to be machined? What are the compromises there?

All experiences and suggestions greatly appreciated.

 

[Tom Welch]

Joe,

Check the archives of this site for results of throttle bodies on otherwise stock engines(mildly modified). I believe that horsepower gain is NILL and you will suffer a torque loss. Change cam and heads and you may see a slight benefit from tb's.

I have the Arrow rockers on my engine and will be putting them on all of our stage 2 cylinder head upgrades as they are a very nice product and fit without modification to the head. As for gains from them alone on stock heads, I can say that on earlier year(pre 00') vipers little to no hp gain. For road racing they enhance the oiling to the valvetrain which is a benefit during sustained high rpm running.

The rockers do enhance power when a cylinder head upgrade is also performed. A combination of enlarged valves, better flowing cylinder ports and the slightly higher valve lift from the rocker ratio add up to a gain in power thats worth doing.

Good luck with your search,

Tom
Http://btrviper.com

 

[treynor]

Seconded. Adding larger TBs to a car with stock heads and stock intake manifold will net you ZIP except for degraded throttle response and loss of low-end. Save your money.

 

[Fred(DrivingSchool)Kinder]

Larger throttle bodies produce ZERO hp gain on stock motors and on motors with ported and polished heads extrude honed intake, CDI headers, etc. Total Waste of money.

 

[ACR Joe]

Thank you all for your wisdom and guidance. I will apply your input wisely and pass on the 1.7 rockers and T/B's.

 

[ACR Joe]

OK, what about a slightly wilder cam with the OEM rockers and throttle bodies?

 

[99 R/T 10]

While we are on the subject, is the stock throttle bodies 55mm or 58mm? Thanks,

Mike